Power amplifiers are widely employed in the telecommunications industry. Telecommunication applications, such as UMTS, WiMAX, high data rate fiber transmission system or microwave systems need power amplifiers that have the ability to amplify wideband signals, e.g. spread spectrum signals in an efficient manner. Since wideband power amplifiers often show gain variations versus the used frequency range, it is difficult to provide the same output power for several frequency bands that shall be covered by the power amplifier.
For example, variable attenuators are used to compensate the gain variations versus frequency.